1. Field of the Invention
The present invention is concerned with the field of grouting application of well casings. In particular, the invention is concerned with a grout wrap including first and second flexible sheets with a layer of flexible, hydrophilic grout material therebetween that expands upon absorption of water. In the preferred embodiment, each well casing section is enclosed by the preferred grout wrap before placement in the well hole, for the purpose of annulas seal between the exterior of well casing and drill hole. After placement, the grout material is exposed to water for absorption so that the grout material expands and seals the annulas space to prevent vertical or lateral movement of surface contamination.
2. Description of the Prior Art
In the prior art of water wells, successive, series connected, well casing sections are lowered into a drill hole approximately 2" larger than casing. For a typical residential well, concrete is then poured into the annulas space between the casing and the walls of the hole. The purpose of the concrete is to seal the exterior of the casing in order to prevent surface contamination into the ground water. This technique is not always successful, however, because the concrete may flow around protrusions from the wall of the hole. As a result, the casing is not sealed in the vicinity of these protrusions.
Another sealing technique, typically used for public wells, is to pump concrete through the interior of the casing so the concrete flows through the casing and then up again along the exterior of the casing. The pumping continues until concrete emerges from this space at the top of the hole. Percussion drilling is then used to clear the concrete from the interior of the casing. However, protrusions between the walls of the hole and the exterior of the casing can still result in voids in the concrete seal thereby exposing a conduit path for the penetration of surface to ground water pollution. It will also be appreciated that these prior art techniques are expensive and the scheduling for sub-contracting times are difficult.